In the water treatment plant different materials are used as filters. The most common been used is/are _____?

In the water treatment plant different materials are used as filters. The most common been used is/are _____?

واٹر ٹریٹمنٹ پلانٹ میں مختلف مواد فلٹرز کے طور پر استعمال ہوتے ہیں۔ سب سے عام _____ استعمال کیا گیا ہے/ہیں؟
Explanation

Sand and gravel are commonly used in filtration to remove impurities and suspended particles from water.

They provide a physical barrier and are effective in both slow and rapid sand filtration processes.